Weighing mechanism



5 Sheets-Sheet 1 Filed Mayl4, 1951 Sept 7, 1954 H. LINDARS WEIGHINGMECHANISM 5 Sheets-Sheet 2 Filed May 14, 1951 Sept 7, 1954 H. LINDARs2,688,477

WEIGHING MECHANISM Filed May 14, 1951 5 Sheets-Sheet 3 Sept. 7, 1954 HLINDARS 2,688,477

WEIGHING MECHANISM Filed May 14, 19751 5 Sheets- Sheet 4 wir...

6lll

lll

5 Sheets-Sheet 5 Filed Hay 14, 1951 Oom:

www5

QON: Om:

xm w Ow: OSE 0 2 m2 I d.. Qd

Patented Sept. 7, 1954 UNITED STATES PATENT OFFICE Claims priority,application Great Britain May 15, 1950 2 Claims.

This invention concerns Weighing mechanisms and has for an object toprovide a mechanism which will enable weight to be ascertained,indicated or recorded to any desired degree of accuracy, if desired at aremote point, and which can also be remotely set to weigh out apreselected quantity of a material, whether solid, iluid, powdered,granular, or in other comminuted form.

It is another object of the present invention to provide weighingmechanism comprising a weghbeam having a plurality of predeterminedpoints of application of a known balancing load or loads, and means forapplying or removing a balancing load to or from a respective point ofapplication to the weighbeam according to the desired balancing momentto be applied thereto.

The balancing loads may be constituted by springs or weights accordingto preference, although weights would normally be employed to avoiddifficulties due to ageing of the springs, and the exact matching ofreplacement springs when these are needed.

The meansfor applying or removing a balancing load preferably comprisesan electromagnet or solenoid, the armature of which is engageable withthe load to lift it clear of the weighbeam or to apply it thereto asrequired, the circuit of the said electromagnet being energised by aswitch which may be either manually or automatically operated.

For the purpose of fine adjustment of the balancing moment applied byone or more balancing loads, a slidable jockey weight may be associatedwith the weighbeam, and an operating motor (which may be separatelymounted or carried on the beam adjacent the fulcrum thereof) may bemechanically connected to the said jockey weight to adjust the positionthereof lengthwise of the beam in known manner. The beam is in balancewhen the jockey weight is in the zero position and no load is applied tothe scale pan or the beam.

Advantageously, the deflection of the beam on either side of the balanceposition is limited by stops which are constituted by electricalcontacts which are connected in a control or indicator circuit. Wherematerial is to be automatically weighed, the said contacts may controlan automatic switching circuit for energising the clectromagnets toapply or remove the balancing loads. Such an automatic switching circuitmay include a rotary selector switch of the telephone uniselector type,the contacts on the various levels of which are connected to theappropriate electromagnets, or a series of relays connected in cascade.

The invention may take a variety of forms according to the particularrequirements of each desired application. Some possible forms will nowbe described, by way of illustration only, with reference to theaccompanying schematic drawings in which:

Fig. l illustrates a simple construction of weighbeam and balancingweights;

Fig. 2 shows a weighbeam arranged as in Fig. l with an associatedelectrical remote control circuit for applying or removing the balancingweights;

Fig, 3 shows a modification whereby an unknown weight is remotelyindicated;

Fig. 4 is a diagrammatic view of an arrangement for obtaining a nesub-division of the smallest unit of increment of balancing moment, and

Fig. illustrates one form of automatic control circuit for ascertainingthe value of an unknown weight of material in the scale pan.

In a rst and relatively simple form of the vinvention and as shown inFig. 1, the weighbeam is constituted by a simple beam l having a lengthof, say, 52 inches, the iulcrum 2 being located 2 inches from one endla. From this end la is Suspended the scale pan 3 or equivalentreceptacle for the material to be weighed out. With no weight in thescale pa'n, and no balancing weight applied to the other end of thebeam, the whole is in balance.

The beam l is provided at intervals along its length with laterallyprojecting lugs 4 which are drilled to form seatings 5 for co-operatingspherical weights 6 which constitute the balancing loads. Just below andcoaxial with each said seating 5 is located a plunger 'l having a cuppedupper end 8 to engage beneath the corresponding spherical weight 6 so asto raise or lower it off or on to the seating 5 under the control of anelectromagnet 9. The plunger is carried on the end of a lever I0 whichis spring loaded at Il to the upper or weight-raising position andcarries the armature l2 of the electromagnet 9, the pull of whichopposes the loading of the spring Il. Energisation of the said magnet 9thus operates to lower the weight 6 on to the beam I. A dashpot i3 isconnected to each beam ID to cushion the shock of applying or lifting aload 6 to or from its seating 5 in the lug 4. Steadies 6a are located soas to receive the several weights 5 in their oif positions.

Above and below the free end lb of the beam I are located respectiveupper and lower limit stops in the form of pairs of electricalcontactsIll, I respectively. These may be connected in circuit with a balanceindicator (not shown) to show at a remote point when the beam i is inbalance. Clearly, the degree of accuracy of a weighing operation carriedout bya mechanism such as has been described is directly dependent onthe number, size and distribution of weights 6 available for providingthe balancing moment. rlhus, for example, if 19 weights of, say, 1 oz.are distributed along the beam as follows: lthe first 9 at distances ofl inch, 2 inches, 3 inches 9 inches respectively from the fulcrum, thenext at distances of 10 inches, 2G inches, 30 inches 100 inchesrespectively from the fulcrum, a balancing moment of from 1 to 595inch-oas. is available in steps of one inch-oz.

By judicious selection of the values and spacings of a few balanceweights E, a wide range of scale pan weights can be balanced. Thus, ii,in the arrangement shown in Fig. 2, there are four weights each of 1oz., and if these are spaced along the beam I at A, B, C and D, atdistances of l0 inches, 20 inches, 30 inches and 40 inches respectivelyfrom the fulcrum 2', it will be seen that ten different moments areavailable:

Moment in Weight inch-02s.

:bouwstenen-1 OOOOOO D|C+BIA Each electromagnet 9' is connected to thepositive main through a respective switch 9A', 9B', 9C', 9D' to a commonset button IB whose cone tacts are normally open, The electromagnets 3.when energised, are operative to apply the appropriate balance weight 6'to the beam I'. The scale pan 3' is located immediately beneath theoutlet Il of a hopper i8 for material to be weighed, the said outlet I'Ibeing controlled by a slide or shutter I9 which is normally biased-as bya spring (not shown)-to the closed position. The shutter i9 isycontrolled by an electromagnet Zil. The circuit to this latterelectromagnet is controlled by a pair of normally open relay contacts F2which are operated by a relay F/2 having its one side earthed and itsother side coni nected to the positive main through a feed button 2i,the contacts of which are normally open. The other pair of contacts FIof the relay F/2 are connected in series with the upper stop contacts Iwhich are arranged to be opened when the weight in the scale pan exceedsthe applied balancing weight and causes the free end Ib of the beam i torise. The other side of the pair of contacts I4' is connected to therelay contacts F2.

In parallel with the electromagnets 9 and their respective switches SA9D' is connected a second relay S/ i whose contacts Si are connected incircuit between the live side of the winding of the relay S/ I and thenormally open contacts FI of the relay F/2.

In use, the operator closes the appropriate switches 9A 9D according tothe required weight of material to be delivered from the hopper I8, andthen presses the set button I6.

This energises the selected electromagnets 9' and the desired balanceweights E are applied to the beam I.

The end I b of the beam I thus falls and the stop contacts Iii areallowed to close. Simultaneously, the relay S/ E is energised and closesits contacts SI which complete the hold-on circuit through the closedcontacts it to both the relay 5,/ I and the selected electromagnets E.

After a brief intervalnsuflicient to enable the dashpot associated witheach balance weight ii to complete its functionthe feed button 2| ispressed momentarily, energising the relay F/Z which closes its contactsFI and F2. Contacts FI complete the hold-on circuit for relay F/2through the contacts ifi (which are still closed). Contacts F2 connectthe positive main to the shutter magnet 2Q, which is then energised toopen the shutter I9 and allow material to discharge from the hopper i8into the scale pan 3.

When the desired weight has been discharged, the end Ib' of the beam Irises against the stop contacts iii and opens them, thus breaking thehold-on circuits to the two relays S/I, F/Z and the electromagnets il'.On the de-energisation of the relay F/Z, the contacts F2 open and theshutter I9 is closed under the action of its spring and no furthermaterial is discharged from the hopper I8 into the scale pan 3.

The apparatus is thus restored to its original state and, after thescale pan 3 has been discharged, will be in readiness for a furtherweighing operation.

As previously indicated, a fairly wide range of diierent scale panweights can be balanced by a few balancing weights of judiciouslyselected values located at appropriate points along the beam I. Thefollowing table shows how, by ernploying only sixteen balance weightseach controlled by a separate switch, such as 9A in Fig. 2, any scalepan weight from 1 lb. to 6 tons, 19 cwts., 3 qrs., 27 lbs. can beweighed in increments of 1 lb.:

No.o1` A Units of Weight balance Individual To*a1 weights 6 moments L 6l, 2, 3, 4, 7, l0 l 27 lbs. 2 1,2 qrs. 5 1, 2, 3, 4, 9 19 cwts. 3 l, 2,3 6 tous.

It will, of course, be evident that, by a similarly appropriateselection of the values and points of application (i. e. moments) of thebalance weights other ranges may be covered in, say, metric units or,for a given material to be weighed, volumetric units such as pints,bushels or the like.

Springs may be used in place of weights for providing the necessarybalancing moments, as. will be understood.

Where the material to be weighed is contained in or discharged into aremovable containerfor example, a truck, bogey, barrow or othertransporting device--the tare weight of the container may first bebalanced, say, by using a separate set of Weights 6 or a jockey weightprovided for the purpose, and then the material may be weighed to thedesired value within the range of the combination of balance weightsprovided. In any such system, it will be appreciated that remoteindication of the weight of material may be desirable, and theindicating apparatus may be so arranged that the weight of any containerused is ignored.

Indication or recording of the weight of an unknown quantity of materialin the scale pan may be effected in any known manner. One relativelysimple method of electrical remote indication comprises causing theapplication of each balancing load to the weighbeam to connect a knownresistance into the measuring circuit. Such an .arrangement isillustrated in Fig.3 of the accompanying drawings. For the sake ofclarity of representation, only the remote indicating circuit is shownin this gure although it will be understood that it may be combined witha remote control circuit such as that shown in Fig. 2.

Each manual weight selector switch 9A" 9D" of the electromagnets 9 inFig. 3 has ganged therewith a second switch 9AX 9DX respectively. Eachof the latter switches is connected to a respective resistance 22A, 22B,22C, 22D which is connected in series with an ammeter 23, so that, onclosure of any one of the switches SAX SDX simultaneously with thecorresponding weight selector switch 9A" 9D", a resistance having avalue corresponding to the moment of the selected weight is connected incircuit with the ammeter 23. The latter may thus be calibrated directlyin terms of weight in the scale pan 3".

Separate iixed stops 24, 25 are provided for the y 26, 21 respectivelyare arranged to be operated by the beam as it approaches thecorresponding xed stop 24, 25. These contact stacks control high,balance and low indicator lamps 28, 29, 30 respectively. The circuitarrangement is as follows: The positive main is connected directly to acontact spring 26a in the stack 26, this spring being engageablev by astud X on the underside of the beam I at its free end Ib. In the balanceposition shown, the said X is out of contact with the spring 26a, andthe latter engages a xed contact 26h. The contact 2Gb is connected to afixed contact 21a in the stack 21 which is normally engaged by a contactspring 2lb connected to the balance indicator lamp 29. The spring 21 bis engageable by a stud Y on the upper side of the beam I opposite thestud X, and carries an insulating block 21m bearing against a .f

second contact spring 21o. In the balance position of the beam I, thestud Y is out of engagement with the spring 2lb so that, in thisposition of the beam, as shown, the circuit from the positive main tothe balance indicator lamp 29 is completed through the spring 26a,contact 26h, contact 21a, and spring 2lb.

When a load is placed in the scale pan 3, the beam I tilts to raise itsfree end Ib against the upper stop 25. At the same time, the stud Ylifts the spring 21h out of contact with the fixed contact 21a, thusbreaking the circuit to the balance lamp 29. Simultaneously, the contactspring 2'Ic is lifted, through the insulating block 21x, to engage afixed contact 21d in circuit with the high indicator lamp 30. The spring21e is connected to the positive main, so that this lamp is nowilluminated.v If now an excess balancing moment is applied to the beam Iby the weight 6, the beam is depressed until its free end Ib engages thelower stop 24. This deiiection causes the upper stud Y to disengage thespring contacts 2lb, 2'Ic, thus opening the circuit to the high"indicator lamp 30, and thereafter the lower stud X engages and depressesthe spring contact 26a until it engages the iixed contact 26e. Thiscontact is connected tc the low indicator lamp 28, and the circuit fromthe positive main to this lamp is thus completed.

It will be appreciated that each time the free end Ib of the beam Iswings from the upper stop 25 to the lower stop 24, and vice versa, thecircuit of the balance lamp 29 will be completed momentarily. The lamps28, 29, 30 together with the switches 9A", SAX 9D", 9DX and the ammeter23 may be located at a remote point so that weighings may be effectedfrom a distance with the same degree of accuracy as can be achieved atthe location of the beam I.

It is only necessary to choose appropriate values for the resistances22A. 22D for a group of four weights to ensure that the operation of thefour weights vsingly or in combination will produce one of elevendefinite readings, including 0. By arranging for the resultantresistances of all groups (say, the hundreds, tens and units groups) tobe switched into circuit with a voltmeter or ammeter, or with arecording voltmeter or ammeter, it is possible to indicate or record thebalancing loads which are operative at any time on the weighbeam I, andtherefore'the total weight which is pre-set or ascertained.

Although, as has already been stated, it will in general be preferred toemploy balance weights rather than springs to provide the necessarybalance moment, the same results are obtainable with such springs, aswill be readily understood. Furthermore, a spring pressure may beapplied to the beam progressively, thus avoiding shock to the systemwhich may otherwise cause undesirable oscillations of the beam ifapplied at or near the balance point in a weighing. This feature ofprogressive application of the balance load may also be usefully adaptedfor the weighing of quantities to an accuracy greater than the unit ofincrement in the balance moment provided by fixed loads applied at fixedpositions. Thus, for example, one balance spring may, for this purpose,be provided with an adjustable abutment which can be moved progressivelyin either direction by a servo mechanism of suitable design. theposition of which can be calibrated in terms of Weight in the scale pan.Such a balance spring would be applied to the beam only when the othersprings had been applied in that combination which produces a balancemoment less than that of the weight in the scale pan by an amount lessthan one unit of increment of the balance moment.

A fine subdivision of one unit of increment in the balance moment mayalternatively be provided, as shown diagrammatically in Fig. 4, by meansof a jockey weight in the form of a subsidiary lever 3I which is pivotedon a carriage 32 movable along a fixed guideway 33 over a distance ofsay 10 inches from the fulcrum 2 (considering the last-mentionedconstruction of weighbeam described above) by a reversing electric motor34 and screw-threaded shaft 35. One end of the subsidiary lever 3l bearsthrough a roller 36 on the weighbeam I". rIhis lever is so loaded as toexert a force of, say, one ounce at its point of bearing on the beam.The balance weights or the like along the beam are indicated at 6"'.

The carriage 32 carries a wiper 31 engaging an electrical resistance 38.By means of an electrical bridge circuit (indicated diagrammatically at39) which includes this resistance, this carriage, and

7 with it the subsidiary lever 3l can be manually or automaticallycontrolled so that it will either take up a denite position, therebyapplying a moment to the lever of, say, from to 10 inchozs. steplessly,or automatically find, by means -of an appropriate electrical circuit(which may include upper and lower limit contacts P, Q and aco-operating contact R operated by the beam l a position which will justbalance a moment exerted by a weight in the scale pan l3'.

A simple form of automatic circuit for the motor 34 is illustratedinFig. 4. Here, the motor Sli is a D. C. reversible motor having the oneends of its forward and reverse windings connected to the D. C. positivemain while the other ends p, g of the windings are connectedrespectively to upper and lower limit contacts P, Q. The cooperatingcontact R carried by the beam l is earthed. The motor 34 thus runs inthe appropriate direction so long as the circuit of the correspondingwinding is completed by the beamoperated contacts P, Q, R. At balance,neither winding of the motor 34 has its circuit completed, and the motoris stationary. The circuit between the motor 34 and the limit contactsP, Q, is broken away and indicated, in the conventional way, by thearrowheads p. g. The circuit 39 may include a remote weight indicatingmeter el), or a suitable dial and pointer mechanism 4l may bemechanically coupled to the shaft of the motor 34.

Alternatively, again, in order to achieve ne subdivision of a unitincrement of balancing moment, a spiral spring may be anchored to thebeam on its fulcrum axis, the other end of the spring being anchored inan adjustable abutment which can be moved by a servo-motor so as toprovide the final fraction of an increment in the balance moment in aweighing operation.

In order that the balance moment should be applied to or removed fromthe weighbeam with a minimum of disturbance to the latter, especiallynear the balancing point, a dashpot mechanism may profitably beincorporated, either in the weight or spring operating mechanism, ordirectly connected to the weighbeam itself. Alternatively, or inaddition to this dashpot mechanism, an electromagnet may advantageouslybe used for the purpose of holding the weighbeam steady through thebalance, actual movement of the weights on to and away from theirseatings on the weighbeam.

Weighing mechanism according to the present invention is of particularlyadvantageous application to remote controlled batch weighing apparatusin which predetermined quantities of one or more materials are required'to be weighed out and discharged according to a pre-set programme.EXamples of such apparatus are described in the specifications ofco-pending patent applications Nos. 183,481 led September 7, 1950, and217,769 filed March 27, 1951. One arrangement of weighbeam which wouldprovide a suitable range of weights is constituted as follows:

The beam is of a nominal length of 52 inches, with the fulcrum 2 inchesfrom the end which carries the scale pan or equivalent receptacle formaterial to be weighed (hereinafter termed for convenience the scalepan). Four balance weights of 1A; oz. are spaced along the beam atdistances of 2, 4, 6 and 8 inches from the fulcrum, four 1/2 oz. weightsat distances 10, 20, 30 and 40 inches from the fulcrum, and four ll-oz.weights at distances of 12%, 25, 371/2 and 50 inches from the fulcrum,By applying the balance weights to the beam in various combinations(which may be effected manually or automatically from a remote point),it is possible to exert any moment on the beam of from 1/2 inch-oz. to555 inch ozs. in increments of 1/2 inch-oz. (5004--l-5 inch-02.); thatis to say, in increments of one part in 1110. In the example quoted,twelve control switches only are required to cover the whole range ofweights. It will be understood by those versed in the art that, by meansof compounding with additional levers, such a weighbeam of 52 inchesnominal length would suffice to balance out considerable loads in thescale pan.

Figure 5 illustrates an apparatus according to the present invention forthe automatic determination of unknown weights of material. The desireddetermination is based on the use of devices known in the art asuniselectors. These devices comprise a series of levels each embodying aset of contacts over which a wiper is movable and they have a stepwiseoperation effected by driving magnets. In such a device, the drivingmagnets are energised through normally closed contacts to move pawlsover ratchet wheels on the driving spindles of respective wipers. Thismovement of the pawls also opens the driving magnet contacts tode-energise the magnets, the pawls then being returned by springs tostep the ratchet wheels and wiper driving spindles round through onecontact pitch on the levels of the uniselector. The action is analogousto that of a single cycle of the trembler of an electric bell and is thestandard operation in the uniselector art.

In Figure 5, the weighbeam iX, fulcrumed at 2X, has a plurality ofbalancing weights (or springs), generally indicated at 6X, distributedtherealong at intervals such that their moments fall into threegroups-units, tens and hundreds respectively-each individual weightbeing identified in thedrawing by the letter M with a numeral indicatingthe corresponding relative moment, e. g. MI, M20, M460. There are fourweights in each group arranged so that increments of moment from 1 to10, 10 to 1GO, or 100 to 1090 respectively, can be obtained in steps ofthe appropriate single units.

Each weight (or spring) 6X is controlled by an electromagnet or solenoid9X which, when energised, applies the respective weight to the beam IX.The free end IbX of the beam is arranged to close a pair of electricalcontacts MX when the moment of the applied weights 93X f is insufficientto balance the moment due to the weight in the scale pan 3X, and upperand lower stops 25X, 24X respectively are provided for limiting thedeection of the beam in the usual way.

Each electromagnet or solenoid 9X has the one end of its winding earthedand the other end connected to the appropriate contacts on a respectivelevel Ll L4 of one of three uniselectors US, TS or HS, representing theunits, tens, or hundreds group respectively. The said connections oneach level are arranged so that, when the wipers are moved from theirzero contacts to the first contacts, all the weights (or springs) 6X ofthe associated group are applied to the beam iX, whilst in thesucceeding positions of the wipers the total moment is reducedprogressively in unit steps to zero. All the contacts, except the Zero:contact, on a fifth level L5 of each uniselector HS, TS, US are strappedtogether and connected, in that order, to the first second or thirdcontact on the fourth level Lt of a fourth uniselector AS. They are alsoconnected, through normally closed relay contacts A3, A4, Arespectively, to their respective housing contacts USdm, TSdm, and HSdmwhich automatically impulse the uniselector driving magnets in the usualway so long as current flows through the circuits. The wipers of thelevels L5 of the uniselectors US, TS, HS are connected to the positivemains, and the wiper of level ASL4 is connected to one of the contactsI4X.

The rst, second and third contacts of the third level L3 of theuniselector AS are directly connected to the driving magnets m, m1 andm2 of the uniselectors HS, TS, US respectively, and the Wiper of levelASL3 is connected, through relay contacts El and B4 to the positivemain. Contacts I, 2 and 3 of level ASL2 are strapped together andconnected through contacts CI and A3 to relay B/4. The wiper of thislevel is connected to the positive main. Contacts I-IU of level ASLI arestrapped together and connected through one side of changeover relaycontacts A1 to the positive main, the zero contact being connectedthrough the other side of changeover relay contacts A1 to the positivemain. The wiper of level ASLI is connected to the housing or self-drivecontacts ASdm of the uniselector AS.

Two keys--CR and AW-are connected in series between the positive mainand a relay A/ 8. The key CR (Cancel Reading) is normally closed whilstthe key AW Ascertain Weight) is normally open. On the depression of thekey AW, the relay A/B is energised and closes the contacts AI, A2, A5and A8, opens the normally closed contacts A3, A4 and A5 and changesover the contacts 41.

The closing of contacts AI completes the holdon circuit for the relay A/8, through the key CR, so that the relay remains energised when the keyAW is released. The closing of contacts A2 connects the positive main tothe wipers on the levels LI L4 of the three uniselectors US, TS and HS,so preparing the circuit for operation of the electromagnets 9X. At thesame time, the opening of contacts A3, A4, and A5, breaks the homingcircuits for the uniselectors US, TS and HS.

The closing of contacts A6 prepares the circuit of the relay E/Z, thecontacts I4 controlled by the weighbeam I being already closed due totilting of the beam by the unbalanced load placed in the scale-pan 3,and the closing of contacts A8 prepares the circuit of the relay B/ 4.

When the contacts A'I change over, the positive main is connectedthrough the 0 contact and the wiper of level ASLI and its self -dri'vecontacts ASdm to the uniselector driving magnet AS, the driving magnetM3 of the other side of which is connected to earth. The uniselector ASthereupon moves one step and then stops, since the rest or" the contactson the level ASLI are disconnected at the change-over contacts A'I.

When the wiper of level ASL2 moves on to contact No. 1, the positivemain is connected through the wiper and this contact, normally closedcontacts Cl, and contacts A3 (which are now closed) to the relay B/4.The latter then operates, closing its contacts BI, B2 and B4 and openingits contacts B3.

The closing of the contacts BI energises the slugged relay D/2, and theclosing of the contacts B2 energises the slugged relay C/I, whichimmediately de-energises the relay B/4 by opening its contacts CI. Therelays E/2, D/2 and C/ I are all slugged relays (referred to hereinafteras single-slugged, double-slugged and treble-slugged respectively), theduration of their release delay periods being so arranged that C/ Iremains operative for the longest time after its circuit has beenbroken, D/Z :for not quite so long and E/2 for the shortest period oftime. Consequently, on the de-energisation of the relay B/ll, thedoubleand treble-slugged relays D/2 and C/ I remain operative for someconsiderable time.

The opening of contacts B3 breaks the circuit to the single-sluggedrelay E/2 and prevents this relay from operating at this point; andsince the doubleeslugged relay D/2 remains energised after the relay B/4is de-energised, the contacts DI serve to maintain this disconnection.

The operation of contacts D2 energises an electromagnet LM which servesto lock the beam IX in the balanced position for the duration of thedelay period of the double-slugged relay D/ 2, and so prevents anyundesired oscillation and vibration of the beam whilst the balanceweights are being changed.

The closing and quick re-opening of contacts B4 connects the positivemain through the normally closed contacts El and the wiper and contactNo. 1 of uniselector level ASL3, to the hundreds driving magnet m ofuniselector HS for a short duration, thus impulsing this uniselectorround one step. Thereupon, all the magnets 9X of the hundreds group areenergised through the closed relay contacts A2 and the No. 1 contacts onthe levels HSLI HSL4. The hundreds weights Mlil M400 are thus applied tothe beam EX which, at this stage, is locked in the balance position.

After a short period of time, sufficient for stability to be attained,the double-slugged relay D/2 releases and the beam locking magnet IM isde-energised, thus allowing the beam to take up its own true position,whilst at the same time the re-closing of contacts DI completes thepreparation of the circuit of the single-slugged relay E/ 2.

In the event of the combined effect of the weights MIDI) M400 beinggreater than the load in the scale pan 3, the beam IX will tilt so thatthe end IbX will come up against stop 24 and the contacts I4X willremain open so that the relay E/2 is not energised. The apparatus willremain in this condition until the end'of the delay period of thetreble-slugged relay C/ I, when this relay will release and reclose thecir cuit to the relay B/4. A further pulse Will then re-energise boththe double-slugged relay D/2 and the treble-slugged relay C/l and movethe uniselector HS on a further step. Contact No. 2 on the level HSLI isopen-circuit, so that on this step the lowest hundreds weight MI isremoved, thus reducing the balancing moment on the beam I by units.

A similar sequence of events is repeated, and in the event of thecontacts I4 remaining open, the whole cycle will be repeated, each timereducing the balancing moment in steps of 100 until it becomes less thanthe moment due to the load in the scale pan 3X.

As soon as free end IbX of the beam I rises to the stop 25 due toover-reduction of the balancing moment, the beam-controlled contacts I4are closed and the positive main is connected to the single-sluggedrelay E/2 through the wiper and bank of level HSLS, contact No. 1 andwiper of level ASL4, closed contacts A5,

l1 and normally closed contacts DI and B3. rlhus the slugged relay E/2is energised.

It will be remembered that at this stage the relay B/ is de-energisedand the double-slugged relay D/2 has just released, but thetrebleslugged relay C/ i is still operative due to its heavier slugging.

The closing of contacts E2 energises the driving magnet m3 ofuniselector AS, and the opening of contacts El breaks the circuit to thedriving magnet m of uniselector HS through the wiper on level ASLS.Release of the trebleslugged relay C/ i occurs before release of thesingle-slugged relay E/Z by a period not less than that required for therelay B/ Il to close its contacts and then release them on de-operationof the action of the treble-slugged relay C/I through its normallyclosed contacts CI, this latter relay being re-energised for the purposeby the relay B/ 4 through its normally open contacts B2. This delayperiod of the single-slugged relay E/Z ensures that the impulse whichWould otherwise be fed through the contacts B4 and the uniselector levelASLS to the hundreds uniselector magnet is suppressed, so that thesetting of the hundreds weights on the beam l is not changed when theuniselector AS changes the circuit connections to the tens uniselectorTS. Similarly, of course, the tens balance weight setting is not changedwhen the uniselector AS changes the circuit connections from the tens tothe units uniselector VS.

On the release of the treble-slugged relay C/ i, relay B/l is energised,opening its contacts B3 and de-energising the single-slugged relay E/2.This relay, however, does not immediately release, and consequently thecircuit to the driving magnet m of the hundreds uniselector HS is notre-made instantaneously. By the time that the single-slugged relay E/2does release, the relay B/i will have been ole-energized by the actionof contacts Cl, relay E/2 remaining deenergised by the opening ofcontacts Dl, and consequently the contacts Bil will have re-opened sothat this pulse from the relay B/d does not operate the hundredsuniselector HS.

On the release of the single-slugged relay E/ 2, its contacts E2 areopened and the driving magnet m3 of the uniselector AS is de-energisedso that the uniselector AS moves its wipers on one step to theircontacts No. 2.

The same chain of events is repeated for the tens uniselector TSL2 whichis stepped through the contact No. 2 on level ASL3. The first step ofthe tens uniselector TS causes all the tens group weight Mill M40 to beapplied to the beam iX. When the double-slugged relay D/2 releasesagain, the locking magnet LM is de-energised and the beam IX is freed.If the increased balancing moment is greater than that of the load inthe scale pan 3X, the contacts MX remain open. The cycle will berepeated, the balancing moment being reduced this time in steps of luntil the beam-controlled contacts MX are again closed. The relay B/llwill then ad- Vance the uniselector AS a further step and the chain ofevents will again be repeated for the units uniselector US. This willapply in its rst step all the units group Weights MI M4, and these willbe reduced in steps of one until the balancing moment becomes less thanthe moment due to the load in the scale pan 3X by an amount which is amaximum of one unit. The beamcontrolled contacts lli will again close,energising the single-slugged relay E/2 which in turn advances theuniselector AS a further step on toV contact No. 4.

At this stage the circuit to relay B/ is broken on level ASL2 and henceno further stepping of the hundreds tens and units uniselectors HS, TS,US respectively, can take place. Moreover, the circuit of the relaylil/2 is broken on level ASL4 and hence the uniselector AS remainsstationary and the apparatus is thus locked in this position.

The position of the wipers on uniselectors HS, TS and US indicates thesum total of the moments that have had to be applied to the beam tobalance the load in the scale pan 3X. Thus, ii' the hundreds HSuniselector is at step No. 4, the moment applied to the beam iX by thehundreds group of weights 6X will be 700 units. If the tens uniselectorTS is at step No. 6, the moment applied to the beam by the tens group ofweights 6X will be 50 units, and if the units uniselector US is at stepNo. 2, the moment applied to the beam IX by the units group of Weightswill be 9 units. Therefore, the total moment applied to the beam will be759 units and this could be conveniently indicated on dials by pointersdriven from the driving spindles of the uniselectors.

On pressing the key CR, the relay A/ is deenergised, opening itscontacts AI, A2, A6 and Ail, closing contacts A3, All and A5 andchanging over the contacts A1.

The opening of contacts AI breaks the hold-on circuit for relay A/ 8;the opening of contacts A2 de-energises the electromagnets 9X, removingthe Weights 6X from the beam iX; the closing of contacts A3, Aliv and A5homes the uniselectors US, TS and HS through their respective levelsUSL5, TSLE and HSLE, whilst the changing over of centacts A1 homes theuniselector AS. The opening of contacts A6 breaks the circuit to therelay E/2, and the opening of contacts A8 breaks the circuit to therelay B/ l1.

The apparatus is thus in its original state and ready to be used againfor ascertaining a further Weight.

By Way of exemplifying the sequence of operation of the various switchesand relays in 5, particulars will now be given listing the same, anillustrative weight being chosen, in this case 654v lbs. The sequence isas follows:

AW (ascertain Weight switch) closed to opcrate relay A/ 8.

Al provides a holding circuit for relay A/ across AW.

A2 connects the positive main to the wipers on the levels LI L4 of thehundreds, tens and units uniselectors.

A3 disconnects the homing arc of the units uniselector level L5.

A4 disconnects the homing arc of the tens uniselector level L5.

A5 disconnects the homing arc of the hundreds uniselector level L5.

A6 prepares the operating circuit for relay E/2.

A1 changes over, disconnecting the homing circuit for AS uniselector andconnecting the positive main to the first contact on ASLl, causing ASuniselector to make one step on to the first contact of the banks.

A8 closes so that ASL2, through the second contact of its bank, connectsup the positive main via Ci and A8 to energise relay B/ BI energisesrelay D/ 2.

B2 energises relay C/ l.

B3 breaks the operating circuit for relay E/ 2.

B4 connects the positive main to the wiper of ASL3 via EI normal andcurrent is now transmitted to energise the drive magnet m` of thehundreds uniselector HS.

DI breaks the operating circuit for relay E/Z.

D2 energises the beam locking magnet coil LM.

CI breaks the operating circuit of relay B/4 which therefore releases.

BI releasing de-energises relay D/2 which remains operated owing to itsdouble slug.

B2 de-energises relay C/I which remains operated owing to its trebleslug.

B3 prepares for the operation of relay E/2.

B4 disconnects the positive main from the wiper of ASL3 releasing thedrive magnet m of uniselector HS, thus allowing the latter to stepforward one contact.

When uniselector HS steps on to the first contact the positive main isapplied by A2 and HSL! to energise the hundred pounds weight and applyit to the beam IX. Similarly the 200, 300 and 400 lbs. weights are alsoapplied to the beam.

D/ 2 relay releases after its delay time.

DI prepares the operating circuit for' relay D2 opens and de-energisesthe magnet LM allowing the beam to take up its true position.

The beam will now go down to its bottom stop 24X as the weight set on itis equivalent to 1000 lbs. and the weight in the weigh hopper 3X isassumed to be 654 lbs., thus the contacts I4 remain open.

After its delay time relay C/I releases cornpleting the reoperatingcircuit for relay B/4.

B/4 operates via CI in normal position.

Sequence as above to stepping of uniselector HS which now steps on tosecond contact.

HSLI opens circuit and releases the 100 lbs weight magnet 9X.

HSL2 holds the 200 lbs. Weight magnet.

HSL3 holds the 300 lbs. weight magnet.

HSL4 holds the 400 lbs. weight magnet.

D/2 relay releases.

C/I relay releases.

B/4 relay operates via CI in normal position.

Sequence as above. Uniselector HS now steps to third Contact.

HSLI re-energises 100 lbs. weight magnet.

HSL2 opens circuit and releases 200 lbs. weight magnet 9X.

HSL3 holds 300 lbs. weight magnet.

HSL4 holds 400 lbs. weight magnet.

D/2 relay releases.

C/ I relay releases.

B/4 relay re-operates via CI in normal position.

Sequence as above. to fourth contact.

HSL! holds 100 lbs. weight.

HSL2 re-energises 200 lbs. weight.

HSL3 opens circuit and releases 300 lbs. weight.

HSM holds 400 lbs. weight.

D/2 relay releases.

C/I relay releases.

B/4 relay re-operates via CI in normal position.

Sequence as above. to iifth contact.

HSLI holds 100 lbs. Weight.

HSL2 holds 200 lbs. weight.

HSL3 re-energises 300 lbs. weight.

HSLII releases 400 lbs. weight.

D/ 2 relay releases.

Uniselector HS steps on Uniselector HS steps on DI prepares theoperating circuit for relay E/2.

D2 de-energises the beam locking magnet LM and the beam I now rises tothe top stop 25 as the Weight in the hopper 3X (654 lbs.) exceeds theweight applied to the beam (600 lbs.).

Contacts I4 close.

E/ 2 relay operates.

EI breaks the operating circuit of the drive magnet m of the uniselectorHS via B4 and ASL3. E2 energises the drive magnet of uniselector AS. f

C/I relay releases after its delay time.

B/4 relay operates via CI in normal position.

BI operates relay D/2.

B2 operates relay C/ I.

B3 releases relay E/2.

E/ 2 relay releases.

E2 de-energises the drive magnet m3 of uniselector AS allowing it tostep forward one contact.

EI connects the positive main to the wiper of ASL3 via B4 thusenergising coil of the drive magnet m1 of uniselector TS.

D/2 relay operates via BI.

D2 energises beam locking magnet LM.

C/I relay operates via B2.

CI releases B/4 relay.

B/4 relay releases.

B4 disconnects positive via El and ASL3 from the drive magnet m1 ofuniselector TS allowing.' it to step forward one contact.

Bl releases relay D/Z.

B2 releases relay C/ I.

TSLI energises the 10 lb. weight magnet 9X.

TSL2 energises the 20 lb. weight magnet.

TSL3 energises the 30 lb. weight magnet.

TSL4 energises the 40 lb. weight magnet.

D/2 relay releases.

C/I relay releases.

B/ 4 relay operates via CI in normal position.

Sequence repeats as above to stepping of uniselector TS which moves onto the second contact.

TSLI releases 10 lb. Weight magnet 9X.

TSLZ holds 20 lb. weight magnet.

TSL3 holds 30 lb. weight magnet.

TSL4 holds 40 lb. weight magnet.

D/2 relay releases.

C/ I relay releases.

B/ 4 relay operates yviaCI in normal position.

Sequence repeats as above to stepping of uniselector TS which now moveson to the next contact.

TSLI re-energises l0 lbs. weight.

TSLZ releases 20 lbs. weight.

TSL3 holds 30 lbs. weight.

TSLI! holds 40 lbs. weight.

D/2 relay releases.

C/ I relay releases.

B/4' relay re-operates via CI in tion.

Sequence as above. to the next contact.

TSLI holds l0 lbs. weight.

TSL2 re-energises 20 lbs. weight.

TSL3 releases 30 lbs. weight.

TSL4 holds 40 lbs. weight.

D/ 2 relay releases.

C/I relay releases.

B/4 relay re-operates via CI in normal position.

Sequence as above. Uniselector TS steps on to next contact.

TSLI holds l0 lbs. weight.

normal posi- Uniselector TS steps on TSL2 holds 2O lbs. Weight.

TSL3 re-energises 30 lbs. weight.

TSL4 releases 40 lbs. weight.

D/ 2 relay releases.

C/ I relay releases'.

B/II relay re-operates via CI in normal Dosition.

TS uniselector steps on to next contact.

TSLI releases 10 lbs. weight.

TSL2 holds 20 lbs. weight.

TSL3 holds 30 lbs. weight.

TSLLl releases 40 lbs. Weight.

D/ 2 relay releases.

DI prepares the operating circuit for relay E/Z.

'D2 de-energises beam locking magnet LM and beam IX now rises to the topstop X since the Weight in the hopper 3X (654 lbs.) exceeds weightapplied to beam (650 lbs.).

Contacts I4 close. Relay E/Z operates.

EI breaks the operating circuit for uniselector TS via B4 and ASL3.

E2 energises the drive magnet m3 of the uniselector AS.

C/I relay releases after itsv delay period.

B/ 4 relay operates via CI in normal position.

BI operates relay D/ 2.

B2 operates relay C/ I.

B3 releases relay E/2.

E/2 relay releases.

E2 de-energises the drive magnet m3 of the uniselector AS allowing it tostepI4 on to the next contact.

EI connects the positive main to the wiper of ASL3 Via Bd, thusenergising the driving magnet m2 of uniselector US.

D/I relay operates via BI.

D2 energises LM.

C/I relay operates via B2.

CI releases relay B4.

B/ 4 relay releases.

`Bil disconnects the positive main via EI and ASLS from the drive magnetm2 of uniselector US, allowing the uniselector to step forward onecontact.

USLI energises l lb. weight magnet.

USL2 energises 2 lb. weight magnet.

USL3 energises 3 lb. weight magnet.

USLII energises 4 lb. weight magnet.

D/ 2 relay releases.

C/ I relay releases.

B/4 relay operates via CI in normal position.

Sequence as above. Uniselector US steps on to next contact.

USLI releases l 1b. Weight.

USLZ holds 2 lb. weight.

USL3 holds 3 lb. weight.

USL4 holds 4 lb. weight.

D/2 relay releases.

C/I relay releases. B/II relay re-operates via CI in normal position.

USLI holds 1 lb. weight.

USL2 re-energises 2 lb. weight magnet.

USL3 releases 3 lb. Weight.

USLd holds 4: lb. Weight.

D/2 relay releases.

C/I relay releases',

B/ 4 relay operates via CI in normal position.

USLI holds 1 lb. Weight.

USL2 holds 2 lb. weight.

USL3 re-'energises 3 lb'. Weight magnet.

USL4 releases 41h. weight.

D/ 2 relay releases.

C/I relay releases.

B/ 4 relay operates via Ci in normal position.

USLI releases l lb. weight.

USL2 holds 2 lb. Weight.

USL3 holds 3 lb. weight.

USL4 releases 4 lb. weight.

D/2 relay releases.

C/ I relay releases.

B/ Il relay operates via CI in normal position.

USL! re-energises l lb. weight magnet.

USL2 releases 2 lb. weight.

USL3 holds 3 lb. Weight.

USL!! releases 4 lb. weight.

D/2 relay releases.

Di prepares for the operation of relay E/Z.

D2 de-energises the beam-locking magnet LM and the beam iX, now rises tothe top stop 25X as the Weight in the hopper 3 equals the weight appliedt0 the beam.

Contacts MX close. (It should be noted that the contacts I$ inpracticewould probably not close until a further Weight had been removed fromthe weighbeam).

E/Z relay operates.

Ei breaks the operating circtut of the drive magnet m2 of uniselector USvia Bil` and ASLB.

E2 energises the drive magnet m3 of the uniselector AS.

C/ I relay releases after its delay time.

B/ 4 relay operates via CI in normal position.

B! operates relay D/2.

B2 operates relay C/ I.

B3 releases relay E/ 2.

E/2 relay releases.

E2 de-energises the drive magnet m3 or" uniselector AS allowing thelatter to step forward one contact.

ASL2 contact il is open circuit and thus relay B/ l is released and willnot reeoperate.

No further operations occur in the circuit until the Cancel Reading pushbutton CR is operated to release relay A/S when the uniselectors arehorned via the normally closed contacts A3, All, A5, A'i.

Modications in design or arrangement of the balancing weights or springsand of their con trolling mechanisms may be made to suit individualrequirements. The' automatic control circuit may also be designed tosuit the particular circumstances or" the operation of the invention, aswill be understood. For example, pneumatic or hydraulic servo systemsfor operating the balancing weights or springs may be adopted ifdesired.

A diiriculty which is inherent in the accurate measurement of materialsdelivered from a hopper (cf. Fig. 2), is that there is always, at theinstant when balance is actually achieved' and the hopper outlet I'Iclosed by the shutter IS, a certain quantity of material in transitbetween the hopper outlet I'I and the scale pan. rhis column insuspension may, for a given apparatus, be of substantially constantdimensions, and a correction can, in these circumstances, be made byadjustment of the actual values, or of the points of application, of thevarious balance weights. In many cases, however, the weight of thecolumn in suspension will be indeterminate and variable, and in thesecircumstances, adjustable resilient contact operating means may beassociated with the free end of the weighbeam which Would operatesufficiently in advance of the raising of this end to the balance'position to ensure early partial closure of the slide i9 or like outletcontrol means.

One application of the present invention is to the loading of vehicleshaving differing tare Weights with the same Weights of material. In

such an application, the vehicle is stood, empty, on a weighbridgeconnected to a weighbeam and the tare weight is first ascertained,either manually or automatically, in a manner set out albove. Whenbalance has been achieved, the additional predetermined weight ofmaterial to be loaded is added to the beam and discharge thereof intothe vehicle is automatically controlled, as described above. Otherapplications of the invention will readily occur to those who areconversant with the art of weighing out quantities of materials ordetermining the value of unknown Weights of material.

What I claim is:

1. Weighing mechanism comprising a weighbeam having a plurality of fixedstations spaced from the fulcrum thereof by predetermined distances forthe application of balancing loads thereat, a plurality of knownbalancing loads arranged in groups, the members of each group beingchosen so that, by selective application of any one or more of saidloads in said group, any one of a set of balancing moments differingfrom another in the set by unity in a scale appropriate to the group maybe applied to the beam, the scales of all the groups differing by apreselected ratio-for example, a ratio of ten, an electromagnetic deviceassociated with each balancing load for applying and removing it to andfrom the beam as desired, a load uniselector switch associated with eachgroup and having a plurality of contact fbanks, one foreach load in thegroup, the contacts of a bank being arranged to energise theelectromagnetic load applying devices so that progressive step-by-stepoperation of the said load uniselector causes progressive application ofthe loads in the group for exerting a balancing moment on the beam whichvaries in steps of unity on the scale appropriate to the group, a

sequence control uniselector switch having a con.

tact bank successive contacts of which are connected incircuit with thedriving magnets of corresponding load uniselectors, an impulsing relayhaving a pair of make-and-break contacts connected in series with thewiper of the said control uniselector contact bank, relay meansresponsive to deections of the beam for impulsing the controluniselector driving magnet, this relay means comprising a single sluggedrelay having a delayed release period at least as long as the periodrequired for the load uniselector impulsing relay to perform a completeimpulsing cycle, a pair of normally open contacts connected directlybetween the main power supply and the driving magnet of the sequencecontrol uniselector, and a pair of normally closed contacts connected inseries with the normally open load uniselector impulsing contacts of thesaid impulsing relay so as to suppress a load uniselector advancingimpulse during advance of the control uniselector, a double sluggedrelay having a delayed release period greater than the period requiredfor the beam to reach a stable condition after a change in appliedbalancing moment, a pair of normally open contacts controlled by thelast-mentioned relay, a beam clamping electromagnet connected in circuitwith the said slugged relay contacts, and a pair of normally opencontacts operated. by the load uniselector impulsing relay and connectedin the double slugged relay circuit for energizing the said relay ateach change of balancing moment.

2. Weighing mechanism according to claim l including a treble sluggedrelay having a delayed release period greater than the delayed releaseperiod of the double slugged relay and a pair of normally closedcontacts in the circuit of the impulsing relay and controlled by saidtreble slugged relay to control the commencement of operation of thesequence control uniselector to apply suc-'- cessive increments ofbalancing moment to the weighbeam and to complete a homing circuit forrestoring the uniselector to its zero position on completion of aWeighing operation.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 618,384 Richards Jan. 24, 1899 1,624,588 Essmann Apr. 12, 19271,661,556 Bryce Mar. 6, 1928 1,719,482 Mills July 2, 1929 2,066,762Bryce Jan. 5, 1937 2,068,565 Okey Jan. 19, 1937 2,594,157 Hadley Apr.22, 1952

